I just saw all the Private messages asking questions that stopped about a year ago. Im sorry for not relying. I've been VERY busy and once I had a really solid grasp, all I was doing was answering the same questions over and over.
Anyways:
After over 3 years(maybe 4, it was November when it first came out) of weekly gigging, Im happy to say my M50 is STILL in top working order.

The ONLY issue I've had, was the LED in one of the red buttons (combi) burned out in the first 6 months. Korg offered to fix it, but I couldnt find time to send it in/drop it off. I needed the instrument. Im sure it's something simple, eventually I may tear it apart and fix it myself.
This was heavy road use (but in a good case).
Last night in my studio, a guy asked "is that new"(asking of my M50). It made me think just how solid of a work horse this work station has been for me.
The sounds (JUST LIKE when I first got it and did some studio work with it) are STILL amazing. Spend some time, you can find a sound close, them mess with it and like magic, it's close enough to perfect than nobody notices live.
The touch screen held up PERFECTLY! I was originally concerned about scratches. But it literally does not have a single scratch on it. (During a gig, I RARELY if ever have to touch it after loading any click tracks (songs) I need.
The bed (keys) are still looking GREAT! Limited scratches. ALL still work perfect.
All knobs are fine, but they NEVER get touched live (I play guitar or bass as a primary instrument in all my bands, so the keys only get utilized may 10 to 20 songs a night, some songs, the M50 is basically a click track.
I was always REALLY careful setting up the power supply and after about a year, I rigged it so the power supply stayed in the unit. It's the one thing that concerned me from day one for heavy gigging. Maybe I was lucky or maybe it's more durable that it appears, either way, mine is problem free!

I wonder if a thread ever got posted on duplicating songs, and sharing them with each other? I always thought that would be cool, besides the fact I personally had 50 songs setup, and very few others had any songs.
I truly hope everyone else doing heavy gigging on a M50 has had the same luck that I have had. For my use, the M50 was without a doubt the PERFECT workstation for me. For programming, I'm sure having the ability to sample like the M3 would have saved me some minimal time setting up songs, but I got through it making sounds VERY close to my goal.
For those of you just looking for a cool workstation for in the studio (Or in your bedroom), you will not go wrong with the M50 (even tho the M3 will do a little more{Vocator and Sampling are really the only two that means a lot, relitively speaking}). In the studio, I have a vocator and the ability to fire samples, so for me, I only needed the heart of the M50 for simple gigging. (I want everything in my personal backline to be SIMPLE!)
I hope this info. helps someone not sure on the M50 compared to the Yamaha equivelant. GO WITH THE KORG! GREAT INSTRUMENT, easy to learn (READ the entire manual AND try everything, plan on 200 hours to truly know the instrument to it's full capability).
Lates!
Studioman
My M50 never fell without being in it's case (luckily:).